Ribbed pipe coupling



FIG. 1 is an isometric view of our design for a ribbed pipe coupling;

FIG. 2 is a front view of the design for a ribbed pipe coupling shown in FIG. 1, the rear view being identical;

FIG. 3 is a top view of the design for a ribbed pipe coupling shown in FIG. 1;

FIG. 4 is a bottom view of the design for a ribbed pipe coupling shown in FIG. 1; and,

FIG. 5 is a left side view of the design for a ribbed pipe coupling shown in FIG. 1, the right side view being identical. 

We claim the ornamental design for a ribbed pipe coupling, as shown and described. 